Apparatus for determining when a patient is susceptible to defibrillation

Abstract

An apparatus for determining when a patient is susceptible to defibrillation comprises a plurality of electrodes ( 12, 14 ) for obtaining an ECG signal from a patient, and data processing means ( 30, 42 ) for determining a region of the ECG signal where the signal passes from a first threshold to a second threshold at least equal in magnitude but of opposite polarity to the first threshold while the gradient of the signal remains within certain limits, detecting the next following ECG signal peak, and providing an output signal upon such detection.

1. An apparatus for determining an instant to apply a defibrillation voltage to a patient, the apparatus comprising a plurality of electrodes for obtaining an electrocardiographic (ECG) signal from a the patient, and data processing means for (a) determining a region of the ECG signal where such ECG signal passes from a first threshold to a second threshold at least equal in magnitude to that of the first threshold and of opposite polarity thereto while the gradient of such ECG signal remains within certain gradient limits, (b) detecting the next following ECG signal peak, and (c) providing an output signal upon such detection, wherein said output signal identifies the instant to apply the defibrillation voltage to the patient. 
   
   
     2. An apparatus as claimed in  claim 1 , wherein the first threshold is a negative threshold and the second threshold is a positive threshold. 
   
   
     3. An apparatus as claimed in  claim 1 , wherein the first threshold is a positive threshold and the second threshold is a negative threshold. 
   
   
     4. A defibrillator including an apparatus as claimed in  claim 1 ,  2  or  3  wherein the occurrence of the output signal is used to trigger the application of a defibrillation voltage across defibrillation electrodes. 
   
   
     5. A defibrillator as claimed in  claim 4 , wherein the electrodes providing the ECG signal are also the defibrillation electrodes. 
   
   
     6. A defibrillator as claimed in  claim 5 , wherein the defibrillation voltage is an n-phasic truncated exponential voltage where n is greater than 1. 
   
   
     7. A defibrillator as claimed in  claim 6 , wherein the defibrillation voltage is a biphasic truncated exponential voltage. 
   
   
     8. A defibrillator as claimed in  claim 5 , wherein the defibrillation voltage is a biphasic truncated exponential voltage. 
   
   
     9. A defibrillator as claimed in  claim 4 , wherein the defibrillation voltage is an n-phasic truncated exponential voltage where n is greater than 1. 
   
   
     10. A defibrillator as claimed in  claim 9 , wherein the defibrillation voltage is a biphasic truncated exponential voltage. 
   
   
     11. A defibrillator as claimed in  claim 4 , wherein the defibrillation voltage is a biphasic truncated exponential voltage. 
   
   
     12. A defibrillator as claimed in  claim 1 , wherein the output signal is provided in real time upon detection of the next following ECG signal peak. 
   
   
     13. A method for determining an instant to apply a defibrillation voltage to a patient, the method comprising the steps of obtaining an electrocardiographic (ECG) signal from the patient using a plurality of electrodes, determining a region of the ECG signal where such ECG signal passes from a first threshold to a second threshold at least equal in magnitude to that of the first threshold and of opposite polarity thereto while the gradient of such ECG signal remains within certain gradient limits, detecting the next following ECG signal peak, providing an output signal upon such detection, and applying the defibrillation voltage to the patient upon the occurrence of said output signal. 
   
   
     14. The method as claimed in  claim 13 , wherein the step of providing the output signal is provided in real time upon the detection of the next following ECG signal peak.